Selected 106th overall by the San Jose Sharks in the 2001 NHL Entry Draft, Ehrhoff moved to North America for the 2003–04 season.

He spent one-and-a-half seasons with the Cleveland Barons, the Sharks' American Hockey League (AHL) affiliate, before joining San Jose on a full-time basis beginning in 2005–06.

During his two seasons with the club, he won back-to-back Babe Pratt Trophies as the team's top defenceman and helped them to the 2011 Stanley Cup Finals, where they lost to the Boston Bruins.

[4] Following the NHL growing up, Ehrhoff has singled out Wayne Gretzky, Pavel Bure and Uwe Krupp as his childhood heroes.

[3][7] Ehrhoff consequently decided to stay in Germany and continued in Krefeld's system at the junior level; his father eventually overcame the cancer.

[3][8] After playing in the junior system of the Krefeld Pinguine, Ehrhoff signed a professional contract with the team in 1999, at the age of 17.

[3] He debuted in nine games with Krefeld in Germany's premiere Deutsche Eishockey Liga (DEL), while primarily playing with EV Duisburg of the third-tier Oberliga on loan.

[3] Ehrhoff attended the Sharks' subsequent training camp following the draft, but was returned to Germany as an early cut on 11 September 2001.

With the expectation from Sharks management that Ehrhoff would join their organization either with the NHL club or in the AHL,[10] he was signed to a contract on 22 June 2003.

[13] Aftering helping the Western Conference YoungStars to a 7–3 win over the East, Ehrhoff also did colour commentary during the All-Star Game for a German telecast.

[20] Ehrhoff added eight points over 11 postseason games—first among team defencemen[21]—in his first Stanley Cup playoffs as the Sharks were eliminated in the second round by the Edmonton Oilers.

On 28 December 2007, Ehrhoff was awarded a penalty shot during a game against the St. Louis Blues; he missed against Manny Legace, though the Sharks nonetheless still won, 1–0.

[27] Ehrhoff's personal success coincided with a franchise year for the Sharks, who earned their first Presidents' Trophy as regular season champions in team history with 117 points.

Ehrhoff was traded to the Vancouver Canucks on 28 August 2009, along with defenceman Brad Lukowich, in exchange for prospects Patrick White and Daniel Rahimi.

[31] The deal was done primarily to clear salary cap space in anticipation of the Sharks' acquisition of star forward Dany Heatley from the Ottawa Senators.

[27] Prior to the last game of the regular season against the Calgary Flames, Ehrhoff was awarded the Babe Pratt Trophy as the Canucks' fan-voted best defenceman.

[34] He finished his first season in Vancouver leading all team defencemen with career-highs of 14 goals, 44 points, a +36 rating and an average ice time of 22:47 minutes per game.

They eliminated the Chicago Blackhawks, Nashville Predators and San Jose Sharks in the first three rounds to advance to the Stanley Cup Finals for the first time in 17 years.

Three days ahead of his free agency, 28 June 2011, his negotiating rights were traded to the New York Islanders in exchange for a fourth-round pick in the 2012 NHL Entry Draft.

It was reported that Ehrhoff had turned down the same deal that former defensive teammate Kevin Bieksa had signed the previous day—a five-year, $23 million contract—to remain with the Canucks.

[46] Although the Islanders had three days of exclusive negotiating rights with Ehrhoff, General Manager Garth Snow self-imposed a one-day deadline to sign him.

Unable to agree on a contract (Snow commented that the proposed deal was "well north" of the Canucks' offer), Ehrhoff was traded to the Buffalo Sabres on 29 June in exchange for a fourth-round pick in the 2012 NHL Entry Draft.

[48] Ehrhoff admitted having a desire for the freedom of unrestricted free agency, but was ultimately won over by the Sabres' contract offer and quality as an organization able to compete for the Stanley Cup.

On 23 August 2015, it was confirmed by General Manager Dean Lombardi that the Los Angeles Kings signed Ehrhoff to a one-year, $1.5 million deal.

Ehrhoff struggled to perform to past expectations, and after scoring just 2 goals in 40 games was waived by the Kings and assigned to AHL affiliate, the Ontario Reign on 11 February 2016.

[63] Ehrhoff made his second appearance at the Division I level for the 2002 World Junior Championships in Austria, leading all tournament defencemen with three goals and 10 points in five games.

[67] Two months after his final international junior appearance, Ehrhoff debuted with Germany's senior team for the 2002 Winter Olympics in Salt Lake City.

[74] On 21 December 2005, Ehrhoff was named to the German Olympic team, along with Sharks teammate Marcel Goc, for the 2006 Winter Games in Turin.

[79] Shortly after the Vancouver Canucks were eliminated from the 2010 Stanley Cup playoffs several months later, Ehrhoff joined Germany for the 2010 World Championships.

[81] Leading Germany in average ice time with 23:34 minutes per game, Ehrhoff was named to the Tournament All-Star Team, along with German goaltender Dennis Endras.